The present invention relates to lampholder for a high-voltage lamp. More particularly this invention concerns such a lampholder with quick-connect contacts.
A standard lampholder, for instance for a high-voltage metal-halide lamp, has a ceramic or porcelain socket having an inner end and forming an outwardly open lamp seat defining an axis and adapted to fit with a base of a high-voltage lamp, a base fittable against the inner end, and a contacts in the base intended to make the connection between supply wires and terminals on the lamp,
A standard high-voltage halogen lamp with a G9 base is held in such a lampholder. A U-shaped retaining spring secured to the socket holds the lamp physically in place in the lamp seat while the contacts engage the terminals on the lamp. To this end the contacts are formed as cages which are difficult to manufacture, requiring several stamping and bending steps to make them of a simple rectangular flat metal blank, the contacts being cut and bent from the ends of the blank. The contacts are held in place on the ceramic or porcelain socket by a base that is made of a temperature-resistant plastic, e.g. a liquid-crystal polymer.
Since the lamp gets very hot in use and this heat is transmitted to the contacts, they must be held in the socket part of the lampholder. This is a problem in that ceramic and porcelain are hard to shape to very exact tolerances, so creating accurately shaped and dimensioned seats for the contacts is extremely difficult, resulting in many rejects and increased production costs. Furthermore the assembly process, normally entailing riveting the base to the socket, is fairly complex and difficult, again adding to the holder""s production costs.
It is therefore an object of the present invention to provide an improved holder for a high-voltage lamp.
Another object is the provision of such an improved holder for a high-voltage lamp which overcomes the above-given disadvantages, that is which is of simple and durable construction and which is particularly easy to assemble and, if necessary, disassemble.
A lampholder has according to the invention a socket having an inner end and formed with an outwardly open lamp seat defining an axis and adapted to fit with a base of a high-voltage lamp and with a pair of inwardly open blind contact holes. A base fitted against the inner end and formed at the contact holes with respective contact seats has a floor formed in line with each contact hole with an axially throughgoing aperture. Respective contacts in the contact seats are each formed with an abutment arm extending along a wall of the respective contact hole and a spring arm extending into the respective contact hole and elastically deformable from a rest position closely juxtaposed with the respective abutment arm to a holding position spaced therefrom so that a conductor pushed axially forward through one of the apertures into the respective contact hole will wedge between the respective contact arms.
Thus this lampholder can be back wired with ease, simply by poking a stripped wire end into the contact hole in the back. The electrical connection thus made will be sound and physically strong, resisting withdrawal of the wire with considerable force. The fact that the contact holes are blind ensures that conductors poked into them cannot interfere with other functions of the lampholder and guarantees proper hookup.
According to the invention each of the contacts further has a bight portion lying against the socket and having opposite ends from each of which extends a respective one of the abutment arms and a respective one of the spring arms. Each bight is substantially planar and the arms are bent outward from the bight. The spring arms are bent outward from a point lying between where the respective abutments arms are bent from and the axis. Thus each contact is a simple piece that can be bent into its final shape in the same stamping operation that cuts it from a sheet blank, typically of copper-clad steel. It can be made easily to relatively close tolerances so that, even if the contact holes are less accurately dimensioned, the finished assembly will go together easily and work perfectly.
The socket is formed adjacent each contact hole with an angled face against which the respective spring arm is elastically deformable in the respective holding position. This prevents the spring arm from being bent too far so that it does not plastically deform.
In the rest position each spring arm bears radially outward on the respective abutment arm. Thus even a small-gauge conductor can be solidly gripped.
To contact a terminal of a lamp in the lamp seat each contact is further formed with a lamp-contact arm projecting axially into the lamp seat. This integral arm directly contacts the lamp terminal to conduct electricity between it and the wire in the contact hole.
The base according to the invention is formed with a pair of contact seats snugly holding the respective contacts. In addition the contacts are at least partially sandwiched between the socket and the base so that no extra parts, for instance rivets, are needed to secure the contacts in place.
The base in accordance with the invention is formed of a plastic highly resistant to heat, such as polyphenyl sulfide or liquid-crystal polymer. The socket is formed or ceramic or porcelain.
The base according to the invention is formed with an axially throughgoing central hole and the lampholder further has a clip formed with a bight engaged in the central hole, a pair of arms extending from respective ends of the bight outward into the socket, outer tabs on the arms bearing axially inward on the socket, and inner tabs at the bight bearing axially outward on the floor of the base so that the clip holds the socket and base together. The inner tabs are elastically deformable and press the socket axially outward against the outer tabs. Thus the clip holds the entire lampholder together, eliminating the need for a separate fastener, and even allows the assembly to be taken apart without damage if that becomes necessary at a later date.